1. Field of the Invention
The present invention relates to a combined apparatus comprising both a suspension whose function is to elastically support the weight of a vehicle and a double effect shock absorber, which may be considered to be an energy dissipater, the apparatus being of the oleopneumatic or hydropneumatic type.
2. Description of Prior Art
It has been known for several years to provide similar apparatus.
In the majority of cases the known devices comprise an oil shock absorber in the body of which a bleed piston is mounted at the end of a shaft fixed to the vehicle chassis.
The suspension function of these devices is generally fulfilled by a spring which surrounds the shaft and the shock absorber body.
During the penetration of the shaft into the piston body, because the volume of oil present is incompressible, it is therefore necessary to compensate for the resulting increase of volume caused by penetration of the shaft, this is generally obtained by the addition to the body of the piston a capacity or reservoir containing a compressible fluid, e.g. compressed air or gas.
It is likewise known to position the compressed gas reservoir laterally with respect to the shock absorber, the said reservoir being connected to the base of the cylinder of the shock absorber by a conduit having a system of valves.
Yet, the manufacture of devices having a lateral reservoir is costly.
The invention has as an aim overcoming the above inconveniences by providing a combined shock absorber and suspension which is of simple design which allows for a lower cost of manufacture than conventional devices and which facilitates maintenance.
The invention has as a further aim to provide an independent and compact combination which permits flexions at least equal to or greater in effect than conventional combinations of the same bulk.
To this end the combined apparatus according to the invention is either an oleopneumatic and/or hydropneumatic type comprising two tubes blocked, respectively, at one of their ends and sliding within one another, each of said tubes constituting an oil reservoir, the said reservoirs being separated by a piston fixed at the end of the interior one of the tubes and being provided with means allowing for the bleeding of oil during compression and/or relaxation, the compressed gaseous fluid being only situated in the interior smaller diamter tube such that the total of the capacity of the exterior one of the tubes is utilized in the expansion position as an oil reservoir.
According to another characteristic of the invention, the sliding interior smaller diameter tube is provided at its apex with a zone free of oil and fed with compressed gas such that in the compressed position of the device, the incompressible oil occupies the entire capacity of the interior tube except for said zone.
According to another characteristic of the invention, a threaded cap blocks each of the tubes and at leat one of the caps, which corresponds to the interal or interior sliding tube, is provided with an internal opening of a diameter smaller than the tube which constitutes the compressed air reservoir.